Sliding spool valve

ABSTRACT

A valve, particularly useful to control the operation of a single-acting hydraulic cylinder comprises a valve body bored to receive a spool-shaped valve stem adapted to be freely rotatable therein and to be moved longitudinally to effect the operation of the valve. Power fluid is admitted to the valve chamber at the mid-portion of the stem, and power fluid take-off is made from the mid-portion through a ball check valve, which is opened either by the fluid pressure of the incoming fluid or by being engaged by one rim of the spool when the spool is slid forward, this latter position permitting fluid to flow from the take-off line. The spool, when slid in the other direction, seals the discharge line from the valve body, permitting the full pressure of the incoming fluid to be exerted on the check valve. The spool, in its mid-position, permits the valve to constantly discharge and the ball check valve to remain seated and to hold whatever fluid pressure exists in the take-off line.

United States Patent 1 Bonney [111 3,774,504 51 Nov. 27, 1973 SLIDINGSPOOL VALVE [76] Inventor: Roland W. Bonney, Western Ave.,

[52] US. Cl 91/446, 91/457, 137/596.13, 137/596.2, 137/636, 137/D1G. 2[51] Int. Cl... FlSb ll/08, FlSb 13/04, Fl6k 11/00 PrimaryExaminer-Irwin C. Cohen Att0rney-Lee A. Strimbeck ABSTRACT A valve,particularly useful to control the operation of a single-actinghydraulic cylinder comprises a valve body bored to receive aspool-shaped valve stem adapted to be freely rotatable therein and to bemoved longitudinally to effect the operation of the valve. Power fluidis admitted to the valve chamber at the mid-portion of the stem, andpower fluid take-off is made from the mid-portion through a ball checkvalve, which is opened either by the fluid pressure of the incomingfluid or by being engaged by one rim of the spool when the spool is slidforward, this latter position permitting fluid to flow from the take-offline. The spool, when slid in the other direction, seals the dischargeline from the valve body, permitting the full pressure of the incomingfluid to be exerted on the check valve. The spool, in its mid-position,permits the valve to constantly discharge and the ball check valve toremain seated and to hold whatever fluid pressure exists in the take-offline.

6 Claims, 5 Drawing Figures 1 SLIDING SPOOL VALVE THIS INVENTION Thisinvention is a control valve particularly adapted for use in conjunctionwith a single-acting hydraulic cylinder such as is used to lift asnowplow blade and hold it in a raised position or to place it in alowered float position. However, as will be apparent, the present valvehas many other applications.

In brief compass, the hydraulic valve of this invention consists of avalve body bored to have a cylindrical valve chamber, one end of whichserves as a valve seat. The valve body is also bored to have an outletor discharge port downstream of the valve seat and, upstream in themiddle portion of the valve, an inlet line and a power-fluid take-offline, the latter of which has a normally closed check valve operated byeither the fluid pressure in the valve or by engagement with aspool-shaped valve stem (referred to hereinafter as a spool).

The spool is made to be longitudinally slideable and free-rotatablewithin the valve chamber. One end, the downstream end, of the spool hasan annular face, preferably a lip, that is adapted to seat in the valveseat when pulled thereunder or against. The other end of the spool has atapered shoulder that, when the spool is slid in opposite direction fromits closed position, engages and opens the check valve.

The enlarged ends of the spool present approximately the same surfacearea to the fluid contained therebetween so the valve operates in anapproximately pressure-balanced state, i.e., the spool can belongitudinally moved easily from one of its positions to the otherregardless of the hydraulic pressure.

The check valve in the power take-off line is preferably a ball checkvalve spring biased to be normally closed. A face of the ball extendsinto the valve chamber and is adapted to be engaged and opened by thetapered shoulder of the spool.

The spool remains normally in a mid-position with the discharge lineopen and the check valve closed, and may be spring biased to do so,although such spring biasing is not desirable in some applicationsThus,hydraulic fluid admitted via the inlet line circulates freely throughthe valve and discharge port to return to the hydraulic fluid resevoir.When the spool is moved to its seated position, closing the dischargeline, the hydraulic pressure builds up, opens the check valve and highpressure fluid flows to the hydraulic cylinder. When the spool isreturned to its mid-position, the check valve seats retaining the fluidin the take-ofi line. When the spool is moved in the position oppositefrom its seated or closed position, the discharge line remains open andthe tapered shoulder of the spool engages and opens the check valve,permitting fluid to drain from the takeoff line.

The valve can be left in this last position with the check valve open sothat the load on the take-off line can float, as in the case of asnowplow blade in its lowered position.

The present valve design is simple and uncomplicated Close tolerancesbetween the spool and the glass, etc., are necessary to meet theconditions of use. The action of the valve is simple and positive. Thevalve is admirably suited to being combined with rotary valves whosestems can accept longitudinal movement, as more fully developed inco-pending application, Ser. No. 230,893, filed on even date herewith,and entitled, Rotary Spool Valve, by the present inventor.

THE DRAWINGS FIG. 1 illustrates, in longitudinal cross section, thevalve of this invention, with the spool in its midposition;

FIG. 2 similarly illustrates the center portion of the valve with itsspool in its seated or closed position;

FIG. 3 likewise illustrates the valve with its spool in the oppositeposition to operate the check valve;

FIG. 4 is a section of the valve taken along line IV IV of FIG. 1; and

FIG. 5 is a schematic illustration of the valve as used in conjunctionwith a single-acting hydraulic cylinder.

For simplicity, the same reference numbers for the same parts have beenused in the various figures of the drawings.

DESCRIPTION With reference to the drawings, the valve body is shown at10 and, as can be seen from FIG. 4, it can be made from square stock,although it just as well could be round. The oil inlet port is shown at11 and the discharge port at 12.

The ball check valve and the connection for the power fluid take-offline is shown at 20. The check valve consists of the check ball 21biased in the closed position with a spring 24 held in place by asnap-in ring 22. The ball seats against a seat 23 and, as can be seen,protrudes slightly into the valve chamber.

The valve body 10 is bored to have a valve chamber 13 and a slightlylarger diameter discharge opening 114 with a rim 15 being providedtherebetween as a valve seat, although this rim is not necessary, asexplained,

- infra, rim 15 does, however, give a positive seating of valve body arenot required and slight leaking will not the spool and thus a feel ofthe closed position to an operator. Rim 15 will usually have the sameinternal diameter as bore 13'.

A spool 30, shown with an integral handle, although it could bedetachably mounted, fits in bore 13. It is held in placeby a washer 29against which a spring 32 acts in a large chamber 16 bored into thevalve body. The spring is retained by a nut 33 about the handle, whichis sealed, in this case, against fluid loss by an O- ring 34. Otherpacking gland arrangements could be used and the spring 32 is notnecessary to the operation of the valve. Stop positions on the handle 30external to the valve body could as well be used to tell the operatorwhich of the three positions the valve was in.

The spool 30 is longitudinally slideable within bore 13 from oneoperating position to another, as shown by direction arrow 38. It isalso freely rotatable within the bore as indicated by direction arrow39.

The stem is centrally bored at 311 and at 31a to provide a passagewayfor fluid from behind the spool to escape into the discharge conduit 14.

Near the end of the spool there is provided a sealing lip 35 that matesand seats in rim 115. At the other end, the spool has an outwardlytapered shoulder 36. The inner diameter of lip 35 and the outer diamterof shoulder 36 are the same, so that the area presented by the portion37 below the lip 35 and the shoulder 36 to the axial force of the fluidbetween the two is approximately the same.

Sealing lip 35 can be dispensed with and the inner face of rim 15 canmate with the cylinder portion 37a of the spool abutting taperingportion 37. In this situation, a stop can be placed on handle 30 toprevent the spool from being too far back and out from under the innerface of rim 15. While this form of seating the spool may have someleakage, it is inconsequential to the operation of the valve.

As can be seen from FIG. 1, the intermediate diameter d of spool 30 issmall enough when the spool is in its mid-position to allow ball 21 tofully seat under the action of spring 24 and to retain any pressure thatis confined therebehind. Oil entering through 11 can circulate directlyto the discharge port as shown by the flow arrows, and no or littlepressure is exerted against ball 21.

When, as shown in FIG. 2, the spool is seated against valve seat or rim15, the fluid entering at 11 is forced to act against ball 21, liftingit and allowing the oil to pass into the take-off line and do its work,as shown by the flow arrows.

As illustrated in FIG. 3, when spool 30 is shifted in the oppositedirection from its mid-position, the discharge port is opened andtapered shoulder 36 engages ball 21 lifting it and allowing oil confinedtherebehind to flow out of the discharge port, along with the incomingoil that is being bypassed, again as shown by the flow arrows. Sincespring 32 is not compressed in this position, the spool can be left inthis position to keep the check valve open and allow the load on thetake-off line to float.

It can be appreciated that without effecting the operation of the valve,passage 31 can be plugged at its end and radial bores can be used toconnect passage 31 to the area of the smallest part of the spool, sothat discharge from 31 is out and around lip 35. This arrangement issometimes desirable when the sliding spool valve is ganged with a rotaryspool valve.

In FIG. 5, the valve is connected via line 20 to a hydraulic cylinder 40that has a piston 41 connected by a rod 42 to a weight W that is to beraised or lowered. When the handle 43 at the end of spool 30 is pulledto place the valve in the position shown in FIG. 2, oil enters cylinder40, and the weight is raised. When the handle 43 is returned to thevalves mid-position, as in FIG. 1, oil is trapped in the cylinder, andthe weight remains in a fixed position. When the handle 43 is pushed toput the valve in the position shown in FIG. 3, then oil can escape fromcylinder 41, and the weight lowers.

The desirable simple construction of the valve is quite apparent fromthe drawings. The spool consists of a single machined rod with nomid-diameter larger than the diameter of lip 35. The valve body is of asingle piece of stock simply and easily bored from either end and thesides, and tapped, with the valve chamber having the smallest internaldiameter. Therefore, the spool can be simply dropped into place (fromleft to right in the drawings), without need to fit sectioned pieces together or the use of recessed retaining rings.

If, in operation, the fit of the spool is poor enough to permit oil topass into chamber 16, which, if not relieved, would hinder thelongitudinal movement of the spool, this oil can escape via passages 31and 31a.

I claim:

1. A valve comprising:

a. a valve body bored to have a cylindrical valve chamber one end ofwhich defines a valve-seat, a discharge conduit therefrom downstream ofsaid valve seat and upstream of said valve seat an inlet conduit and apower-fluid take-off conduit;

b. a cylindrical spool slideably mounted within said valve chamber,extending through said valve seat and having (1) an end downstream ofsaid valve seat adapted to mate and form a seal with said valve-seatwhen said spool is in a closed position, (2) a mid-portion of smallerdiameter, both said inlet conduit and said take-off conduit facing thesame when said spool is in a mid-position with said spool end beingunseated, and (3) on the other end an enlarged tapered shoulder nolarger than the diameter of said end; means for sliding said spool fromsaid mid-position in one direction in said valve chamber to said closedposition, and in the other direction to bring said tapered shoulder intothe zone of said mid-position; and

c. a check valve in said take-off conduit at the end facing said valvechamber, said check valve having a valve member normally biased in theclosed position and opening (1) when engaged by said tapered shoulder,and 2) under the pressure of power-fluid in said valve chamber when saidspool is in said closed position.

2. The valve of claim 1 wherein the opposing crosssectional areas of theends of said spool containing power-fluid when said spool is in saidclosed position are approximately equal and the pressures tending tomove said spool in one direction or the other are approximatelybalanced, the interior diameter of said valve seat being approximatelythe same as the largest diameter of said valve chamber.

3. The valve of claim 1 wherein said check-valve is a spring loaded ballcheck valve, the face of the ball of which extends slightly into saidvalve chamber and engages said tapered shoulder.

4. The valve of claim 1 wherein said end of said spool downstream ofsaid valve seat has a radially extending lip of diameter larger than thediameter of said valve chamber, and wherein said valve-seat has a facemating with said lip when said spool is in said closed position.

5. The valve of claim 1 wherein said means for sliding said spoolcomprises:

d. a valve handle connecting with said spool beyond said taperedshoulder and extending from said falve body along the axis of rotationof said spool;

e. means for biasing said spool to return to said midposition from saidclosed position; and

f. sealing means adapted to prevent the passage of fluid between saidvalve body and said valve handle; and wherein said spool has an interiorpassageway adapted to permit fluid to flow from beyond said taperedshoulder into said discharge conduit, and said spool is freely rotatablewithin said valve chamber without effecting the operation of said valve.

6. The combination of the valve of claim 1 with a single actinghydraulic cylinder, the inlet of said hydraulic cylinder being connectedwith said power-fluid take-off conduit.

1. A valve comprising: a. a valve body bored to have a cylindrical valvechamber one end of which defines a valve-seat, a discharge conduittherefrom downstream of said valve seat and upstream of said valve seAtan inlet conduit and a power-fluid take-off conduit; b. a cylindricalspool slideably mounted within said valve chamber, extending throughsaid valve seat and having (1) an end downstream of said valve seatadapted to mate and form a seal with said valve-seat when said spool isin a closed position, (2) a mid-portion of smaller diameter, both saidinlet conduit and said take-off conduit facing the same when said spoolis in a mid-position with said spool end being unseated, and (3) on theother end an enlarged tapered shoulder no larger than the diameter ofsaid end; means for sliding said spool from said mid-position in onedirection in said valve chamber to said closed position, and in theother direction to bring said tapered shoulder into the zone of saidmid-position; and c. a check valve in said take-off conduit at the endfacing said valve chamber, said check valve having a valve membernormally biased in the closed position and opening (1) when engaged bysaid tapered shoulder, and (2) under the pressure of powerfluid in saidvalve chamber when said spool is in said closed position.
 2. The valveof claim 1 wherein the opposing cross-sectional areas of the ends ofsaid spool containing power-fluid when said spool is in said closedposition are approximately equal and the pressures tending to move saidspool in one direction or the other are approximately balanced, theinterior diameter of said valve seat being approximately the same as thelargest diameter of said valve chamber.
 3. The valve of claim 1 whereinsaid check-valve is a spring loaded ball check valve, the face of theball of which extends slightly into said valve chamber and engages saidtapered shoulder.
 4. The valve of claim 1 wherein said end of said spooldownstream of said valve seat has a radially extending lip of diameterlarger than the diameter of said valve chamber, and wherein saidvalve-seat has a face mating with said lip when said spool is in saidclosed position.
 5. The valve of claim 1 wherein said means for slidingsaid spool comprises: d. a valve handle connecting with said spoolbeyond said tapered shoulder and extending from said falve body alongthe axis of rotation of said spool; e. means for biasing said spool toreturn to said mid-position from said closed position; and f. sealingmeans adapted to prevent the passage of fluid between said valve bodyand said valve handle; and wherein said spool has an interior passagewayadapted to permit fluid to flow from beyond said tapered shoulder intosaid discharge conduit, and said spool is freely rotatable within saidvalve chamber without effecting the operation of said valve.
 6. Thecombination of the valve of claim 1 with a single acting hydrauliccylinder, the inlet of said hydraulic cylinder being connected with saidpower-fluid take-off conduit.